www/node20: fix build on powerpc64

../deps/simdutf/simdutf.cpp:8339:37: error: use of 'long long' with 'vector' requires VSX support (available on POWER7 or later) to be enabled
8339 | using vec_u64_t = vector unsigned long long;

|                                     ^

../deps/simdutf/simdutf.cpp:8340:35: error: use of 'long long' with 'vector' requires VSX support (available on POWER7 or later) to be enabled
8340 | using vec_i64_t = vector signed long long;

|                                   ^